Page last updated: 2024-10-24

calcium-activated potassium channel activity

Definition

Target type: molecularfunction

Enables the calcium concentration-regulatable energy-independent passage of potassium ions across a lipid bilayer down a concentration gradient. [GOC:dph, GOC:mtg_transport]

Calcium-activated potassium channels (KCa channels) are a diverse group of ion channels that are activated by an increase in intracellular calcium concentration. These channels play critical roles in a wide range of physiological processes, including neuronal excitability, muscle contraction, hormone secretion, and cell volume regulation. The molecular function of calcium-activated potassium channel activity can be summarized as follows:

1. **Calcium Sensing:** KCa channels possess a specific calcium-binding domain, typically located within the channel's cytosolic region. This domain binds calcium ions, triggering a conformational change in the channel protein.

2. **Channel Opening:** The binding of calcium to the channel's calcium-binding domain leads to a structural rearrangement, resulting in the opening of the channel pore. This allows potassium ions to flow across the cell membrane, down their electrochemical gradient.

3. **Potassium Conduction:** Once the channel is open, potassium ions permeate through the pore, moving from the intracellular compartment to the extracellular compartment. This outward movement of potassium ions can have several physiological effects.

4. **Membrane Potential Regulation:** KCa channels contribute to the regulation of membrane potential by increasing potassium permeability. By allowing potassium ions to flow out of the cell, these channels hyperpolarize the membrane, making it less likely to fire an action potential.

5. **Cellular Signaling:** KCa channel activity can influence cellular signaling pathways by modulating the activity of other ion channels, enzymes, or second messenger systems. This can affect various cellular processes, including neuronal communication, muscle contraction, and hormone secretion.

6. **Cell Volume Regulation:** KCa channels can play a role in cell volume regulation by contributing to potassium efflux. This efflux can lead to water efflux, reducing cell volume.

7. **Modulatory Effects:** The activity of KCa channels can be modulated by a variety of factors, including phosphorylation, membrane potential, and interactions with other proteins. This allows for fine-tuning of channel activity in response to different cellular needs.

In summary, calcium-activated potassium channels are essential for maintaining cellular function by regulating membrane potential, contributing to cellular signaling pathways, and regulating cell volume. Their diverse molecular functions make them crucial players in a wide range of physiological processes.'
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Proteins (7)

ProteinDefinitionTaxonomy
Calcium-activated potassium channel subunit alpha-1A calcium-activated potassium channel subunit alpha-1 that is encoded in the genome of rat. [OMA:Q62976, PRO:DNx]Rattus norvegicus (Norway rat)
Calcium-activated potassium channel subunit beta-1A calcium-activated potassium channel subunit beta-1 that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q16558]Homo sapiens (human)
Small conductance calcium-activated potassium channel protein 2A small conductance calcium-activated potassium channel protein 2 that is encoded in the genome of human. [PRO:CNA, UniProtKB:Q9H2S1]Homo sapiens (human)
Small conductance calcium-activated potassium channel protein 1A small conductance calcium-activated potassium channel protein 1 that is encoded in the genome of human. [PRO:CNA, UniProtKB:Q92952]Homo sapiens (human)
Potassium channel subfamily K member 18A potassium channel subfamily K member 18 that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q7Z418]Homo sapiens (human)
Calcium-activated potassium channel subunit alpha-1A calcium-activated potassium channel subunit alpha-1 that is encoded in the genome of human. [PRO:WCB, UniProtKB:Q12791]Homo sapiens (human)
Intermediate conductance calcium-activated potassium channel protein 4An intermediate conductance calcium-activated potassium channel protein 4 that is encoded in the genome of human. []Homo sapiens (human)

Compounds (12)

CompoundDefinitionClassesRoles
clotrimazoleconazole antifungal drug;
imidazole antifungal drug;
imidazoles;
monochlorobenzenes
antiinfective agent;
environmental contaminant;
xenobiotic
flufenamic acidflufenamic acid : An aromatic amino acid consisting of anthranilic acid carrying an N-(trifluoromethyl)phenyl substituent. An analgesic and anti-inflammatory, it is used in rheumatic disorders.

Flufenamic Acid: An anthranilic acid derivative with analgesic, anti-inflammatory, and antipyretic properties. It is used in musculoskeletal and joint disorders and administered by mouth and topically. (From Martindale, The Extra Pharmacopoeia, 30th ed, p16)
aromatic amino acid;
organofluorine compound
antipyretic;
EC 1.14.99.1 (prostaglandin-endoperoxide synthase) inhibitor;
non-narcotic analgesic;
non-steroidal anti-inflammatory drug
lidocainelidocaine : The monocarboxylic acid amide resulting from the formal condensation of N,N-diethylglycine with 2,6-dimethylaniline.

Lidocaine: A local anesthetic and cardiac depressant used as an antiarrhythmia agent. Its actions are more intense and its effects more prolonged than those of PROCAINE but its duration of action is shorter than that of BUPIVACAINE or PRILOCAINE.
benzenes;
monocarboxylic acid amide;
tertiary amino compound
anti-arrhythmia drug;
drug allergen;
environmental contaminant;
local anaesthetic;
xenobiotic
ns 1619NS 1619 : A member of the class of benzimidazoles that is 1,3-dihydro-2H-benzimidazol-2-one in which the hydrogens at positions 1 and 5 are replaced are replaced by 2-hydroxy-5-(trifluoromethyl)phenyl and trifluoromethyl groups, respectively. It is an opener/activator of the large-conductance calcium-activated potassium channel (Bkca).

NS 1619: structure given in first source
(trifluoromethyl)benzenes;
benzimidazoles;
phenols
potassium channel opener
podophyllotoxinPodophyllum: A genus of poisonous American herbs, family BERBERIDACEAE. The roots yield PODOPHYLLOTOXIN and other pharmacologically important agents. The plant was formerly used as a cholagogue and cathartic. It is different from the European mandrake, MANDRAGORA.furonaphthodioxole;
lignan;
organic heterotetracyclic compound
antimitotic;
antineoplastic agent;
keratolytic drug;
microtubule-destabilising agent;
plant metabolite;
tubulin modulator
triphenylacetic acid
bms204352BMS204352: a calcium-sensitive opener of maxi-K potassium channels; structure in first source
senicapocsenicapoc: a Gardos channel blocker; structure in first source
tram 34TRAM 34: inhibits IKCa1; structure in first sourceorganochlorine compound
n-(4-methylpyridin-2-yl)-4-(pyridin-2-yl)thiazol-2-amineN-(4-methylpyridin-2-yl)-4-(pyridin-2-yl)thiazol-2-amine: calcium-activated small conductance potassium channels inhibitor; structure in first source
n-(pyridin-2-yl)-4-(pyridin-2-yl)thiazol-2-amineN-(pyridin-2-yl)-4-(pyridin-2-yl)thiazol-2-amine: an SK channel inhibitor
N-(5-chloro-2-hydroxyphenyl)-2-ethoxybenzamidebenzamides